This invention relates to picture frames which may be disassembled to permit changing of the print, canvas, photograph or other image contained therein.
It is common practice to provide reusable rectangular picture frames comprising four extruded side members cut to a miter at each end. Each side member is commonly made of metal, to give it the necessary rigidity. It is also formed to provide two channels. One channel is designed to receive the stack of elements to be framed--commonly a backing plate, the image-bearing sheet, and a glass plate. The other channel receives right-angle locking elements, each of which form one pair of ends of a pair of side members into a right angle corner configuration and locks them in that condition. Thus the side members are assembled to form a rigid rectangular frame. The right angle elements typically comprise a pair of L-shaped plates. Screws extend through openings in one such plate and bear against the other plate; thus the plates may be forced apart so that they press against the walls of the channel in which they are disposed and give a friction lock.
A reusable frame therefore involves the following concepts:
1. Rigidity of the frame is required to give strength to the structure;
2. To permit reuse, the frame needs to be formed in sections which are mechanically but releasably locked together to form a unit--the locking devices used also force the sections into a right angle corner configuration; and
3. The sections are formed to provide a bounding channel, to hold the stack of framed elements, and a locking element channel, in which the mechanical locking devices are positioned.
There are certain disadvantages accruing to the reusable picture frames as previously described.
For example, the appearance of the unit cannot easily and cheaply be modified. More particularly, it is frequently desirable to be able to change the thickness of the frame molding or its coloration. Since the front wall of the extruded side member provides the molding in a conventional frame, the only way in which a supplier or user of frames can provide variation in this regard is to maintain a stock of relatively expensive side members having front walls of different thickness or coloration. It is one object of this invention to provide a frame in which the molding thickness or coloration can easily and cheaply be varied.
Another disadvantage of the conventional system is its relatively high cost. The need to make the extruded metal side member so it provides two channels and the use of screws and locking plates contribute to this cost. It is therefore another object of the invention to provide a simpler side member and to eliminate screws and tensioned metal spring clips to thereby reduce the cost of the frame.